To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
In a general communication system, a base station may synchronize time between the base station and a UE using two methods. First, during a call setup, the base station estimates a time offset value of the user equipment (UE) by using a Physical Random Access Channel (PRACH) and then transmits a big Time Alignment (TA) control command to a UE so as to adjust a timing of the UE, thereby allowing time synchronization between the base station and the UE. Second, the base station measures a time offset value of the UE by using a Sounding Reference Signal (SRS) or an RS of a Physical Uplink Shared Channel (PUSCH) and then periodically transmits a small TA control command to the UE to adjust a timing of the UE, thereby allowing time synchronization between the base station and the UE.
The base station may adjust the timing of the UE to a time point desired by the base station using the two methods described above. In general, a time offset value is a cause of lowering the link performance. When the time offset value is zero, performance degradation does not occur due to the time offset value. Therefore, it is important to control the timing of the UE such that the time offset value of the UE is to be zero.
However, even when the timing is periodically adjusted, a timing mismatch between UEs may occur because of the movement of the UE or other different reasons. In a state where the timing of the UE is adjusted to zero, and when the timing between the UEs is mismatched due to specific reasons of the UE, an Inter Symbol Interference (ISI) may occur due to a Timing Advance (TA) indicating that a signal transmitted by the UE arrives earlier than the reference timing.
Accordingly, the present invention is to provide a method capable of reducing an ISI occurring due to an offset value between the reference timing and a timing at which a signal transmitted by the UE is received.